Eq. (2.11) represents the elastic energy of a network with polydisperse strands where all strands are assumed to be elastically active. The free energy function presented by Eq. (2.7) accounts for the finite extensibility of flexible strands and diverges as the stretch approaches the ultimate locking value of \(\lambda _{lock}=\sqrt{j}\)  [1]}. Assuming that crosslink points move in an affine fashion, shorter strands are expected to experience a larger entropic tension. As proposed by Itskov and Knyazeva [2]}, the highly extended strands snap at some finite stretch and become elastically inactive. Therefore, at each direction, strands shorter than a certain length break and do not contribute to the energy function (2.11). The ultimate strength of an elastically active strand is determined either by scission of bonds along the backbone or cleavage of a crosslink. The activation energy for rupture is directly related to the nature of interatomic potential or the dissociation energy of crosslink coagents. Different harmonic and anharmonic potential functions have been used to present the energy landscape of interatomic dissociation in polymer chains [3]}, [4]}, [5]}, [6]}. The Morse potential, for example, is used to predict the stiffness of a covalent bond in a nan-Gaussian polymer chain during cleavage [7]}. Here, a Morse pair-potential is used to describe the energy barrier of debonding. That is
\( U(r)=U_{0}\Big (1-e^{-\alpha (r-r_{0})}\Big )^2\) 
